Steve, (and this is really IMHO), the advice given above (talk to the salespeople) is quite good.
Beyond that, a knowledge of what *not* to buy, and a knowledge of what attributes of various skis affect how they ski will be nice to know.
Pick up a ski magazine which has some ski reviews and read what they say. You probably do not want any kind of racing ski ( i can say that definitively). Beyond that, you really need to look at the options and see for yourself.Skis are designed for different things, and you probably won't notice the difference between any of the top of the line skis, assuming they are designed for the same thing (i can't tell, never having skiied top of the line skis
One thing I can say is that you probably do not want a huge tail sidecut, that is, Let's say the tip is 110 cm and the waist is 70 cm. If the tail is 106 cm, it will have the tendancy to lock you into turns, which is not a bad thing the way some people ski. However, if you're beginning, you want the ability to smear your turn, so look for something with a bit less sidecut at the tail. This is just IMO, i ski skis like this at hi speeds, but i find this works really well if i have to make quick turns.
I hope this helps, although it was mostly my rambling.